Over the past several decades the use of spark-ignited two-cycle (2-stroke) internal combustion engines has steadily increased. They are presently found in power lawn mowers and other power-operated garden equipment, power chain saws, pumps, electrical generators, marine outboard engines, snowmobiles, motorcycles and the like. Two-cycle engines have found limited application as automobile and truck engines. Manufacturers are exploring how to expand this use.
The increasing use of two-cycle engines coupled with increasing severity of the conditions in which they have operated has led to an increased demand for oils to adequately lubricate such engines and which provide enhanced performance. Among the problems associated with two-cycle engines are piston ring sticking, piston scuffing, rusting, lubrication related failure of connecting rod and main bearings and the general formation on the engine's interior surfaces of carbon and varnish deposits. Piston ring sticking is a particularly serious problem. Ring sticking leads to failure of the sealing function of piston rings. Such sealing failure causes loss of cylinder compression which is particularly damaging in two-cycle engines because these engines depend on suction to draw the new fuel charge into the exhausted cylinder. Thus, ring sticking can lead to deterioration in engine performance and unnecessary consumption of fuel and/or lubricant Other problems associated with two-cycle engines include piston lubricity, scuffing or scoring.
All of the aforementioned problems associated with two-cycle engines must be adequately addressed Improved performance is continually being sought. The unique problems and techniques associated with the lubrication of two-cycle engines has led to the recognition by those skilled in the art of two-cycle engine lubricants as a distinct lubricant type. See, for example, U.S. Pat. Nos. 3,085,975; 3,004,837; and 3,753,905.
The compositions of the present invention are effective in controlling the aforementioned problems.
While color, per se, is not often a consideration when evaluating performance of a 2-cycle engine lubricant, it may be a consideration for other reasons.
As is well-known, the equipment operator frequently prepares lubricant-fuel blends. A particularly dark colored lubricant or one that imparts a significant color to the lubricant-fuel blend, while not affecting performance, may be deemed to be objectionable. Furthermore, two-cycle oils frequently contain a small amount of dye, to impart a characteristic color to the lubricant-fuel blend. If the color of the lubricant is pronounced, it may mask the color of the dyed fuel or may lead the user to believe that the lubricant-fuel blend has deteriorated.
The lubricating compositions of the instant invention are considerably lighter in color than many commercially available lubricants.
U.S. Pat. No. 4,425,138 relates to amino phenols used in lubricant fuel mixtures for two-cycle engines U.S. Pat. Nos. 4,663,063 and 4,724,091 issued to Davis relate to a combination of an alkyl phenol and an amino compound in two-cycle engines.
U.S. Pat. Nos. 4,708,809 and 4,740,321 relate to use of alkylated phenols in two-cycle engine lubricants. U.S. Pat. No. 4,231,757 relates to nitrophenol-amine condensates and the use thereof in two cycle oils.